Question

Ethanoic acid is-
[A]$C{{H}_{3}}COOH$
[B]${{C}_{2}}{{H}_{5}}COOH$
[C]$HCOOH$
[D]$HCHO$

Answer 1

Hint: Ethanoic acid is a carboxylic acid. Ethanoic acid is the IUPAC name of acetic acid, which is a carboxylic acid to which a methyl group is attached.

Complete answer:

Ethanoic acid is also known as acetic acid or when in undiluted form, it is also called glacial acetic acid.
Ethanoic acid is a colourless liquid organic compound with a pungent smell and sour taste.
Acetic acid is used in making vinegar. Vinegar is 4% acetic acid and 96% water.
Acetic acid is a weak acid and dissociates partially in solution but glacial acetic acid can cause harm to our skin.
Acetic acid is the second simplest carboxylic acid, first being formic acid. It consists of a methyl group to which a carboxyl group is attached. Its name can be derived from ethane which has the formula ${{C}_{2}}{{H}_{6}}$ where, one methyl group is replaced by a carboxyl group, hence giving it the name ethanoic acid.

The chemical formula of ethanoic acid is $C{{H}_{3}}COOH$.
Therefore, the correct answer is option [A]$C{{H}_{3}}COOH$.

Additional Information:
Ethanoic acid is an important chemical reagent and is also used industrially in the production of cellulose acetate which is used in photographic film and polyvinyl acetate for making wood glue. It is also used in households to remove limescale from metal surfaces which are in contact with hot water like water heaters and kettles. It is also used in the food industry as an acidity regulator.


Note:
If such a question is given to us where IUPAC name of the acid is mentioned and we have to find its formula, we can look at the number of carbon atoms present in it, like methanoic acid will have one carbon so HCOOH is methanoic acid. Similarly ethanoic and propanoic acid will have 2 and 3 carbons respectively. So $C{{H}_{3}}COOH$is ethanoic acid and ${{C}_{2}}{{H}_{5}}COOH$ is propanoic acid.